However, given the position we have set out here, the justification for seeking a specifically causal model to represent the realities underlying quantum mechanics seems somewhat unclear. After all, if one agrees that `causality' in the usual sense arises from causal order plus a choice of direction, then not only is there no reason to expect a classical causal model to work in the context of the Bell correlations and other nonlocal quantum phenomena, there is no obvious reason to expect any other kind of causal description to work either - the conditions which typically give rise to the appearance of causal phenomena are absent, and in their absence why should we expect that the underlying reality should have causal features at all? Thus this emphasis on explaining quantum mechanics in terms of a `nonclassical theory of causation' seems too limiting: for example, both classical and quantum causal models are required to obey a Markov condition, so presumably any further `nonclassical theory of causation' would also obey such a condition, but if we are really seeking to understand the reality underlying quantum mechanics it's not very clear why we should restrict our attention to models with this feature, and indeed several authors have argued that realistic models for quantum mechanics should not obey a Markov condition[1]}, [2]}. Similar points can be made for other features of causation which ref [3]} would wish to preserve in a nonclassical causal theory; while it could certainly turn out to be the case that the reality underlying quantum mechanics does in fact have some of these features, and one might reasonably decide pragmatically to begin the search for possible models by looking at models with these features, nonetheless we should not rule out other possibilities just because they don't look sufficiently `causal' to our classical intuition.
